Question

rules for active and passive voice

Answer 1

the object of the active sentence becomes the subject of the passive sentence.

the finite form of the verb is changed (to be + past participle)

the subject of the active sentence becomes the object of the passive sentence (or is dropped)

Answer 2

Passive Voice for all Tenses - Rules
There are two basic rules for converting sentences from Active Voice into Passive Voice, which are common for all tenses.
The places of subject and object will be interchanged in the sentence.
Only 3rd form of the verb or Past Participle (e.g. written) will be used as a main verb in Passive Voice.